[R] Get means of matrix
Jesús Para Fernández
j.para.fernandez at hotmail.com
Wed Nov 18 11:19:49 CET 2015
Hi everyone
I have a dataframe "data" wich is the result of join multiple csv (400 rows and 600cols every csv). The "data" dataframe has n rows and m columns (200000 rows and 600 cols) , and I have add a new colum, "csvdata", in which I specify the number of csv at wich those data belong.
So, the dataframe "data" looks like:
x1 x2 x3 .... xn csvdata
21 23 32 .... 12 1
27 21 39 .... 14 1
24 22 30 .... 11 1
..............................................
21 24 32 .... 19 2
27 21 39 .... 14 2
..............................................
27 22 30 .... 11 n
I want to store into a matrix the mean values of different substes of data of every csv, for example:
region1,1 (rows 1:20,columns 1:20) for every "csvdata" value
region 2,1 (rows 21:40,columns 1:20) para every "csvdata" value
....
And so on for hole data.frame.
I have tryed:
area1<-tapply(as.matrix(data[1:20,1]),datos$csvdata,mean,na.rm=T)
area2<-tapply(as.matrix(data[1:20,1]),datos$csvdata,mean,na.rm=T)
But this error is the output I obtain:
Error in tapply(data[1:30, ], datos$nueva, mean, na.rm = T) :
arguments must have same length
I´m sure that it is not very complex to do it, but I have no idea of how to do it.
Thanks for all.
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